Nirn (believed to mean 'Arena' in Ehlnofex) is the planet on which the Elder Scrolls is set. It floats in the void of Oblivion and is, for all intents and purposes, the majority of the realm known as Mundus.[1] Sources often use the terms Nirn and Mundus synonymously, despite the technical differences in the two terms. Nirn was created during the Dawn Era by the Aedra and Anu-aligned spirits, based on Lorkhan's inspiration[2] and Magnus' designs.[3][4]

Nirn has two moons, Masser and Secunda.[10] The other astral bodies in the sky above Nirn are believed to actually be the spheres of the Aedra and Daedra, as seen from the mortal plane. The sun and stars are also punctures in the veil of Oblivion, through which the light of Aetherius shines into Mundus. One exception is the snake constellation, The Serpent, which 'wanders' about the sky.[11] It is made up of "unstars".[oog 1]

For an account of Nirn's mythic history, see the article on the Mundus.